Hitherto, many preparations have been developed and marketed as antitumor drugs. However, with the exception of a few products, they are limited for oral administration and for intravenous adminstration. Also, a considerable number of these antitumor drugs may have an excellent antitumor activity but they cause harmful side effects.
Now, if an antitumor drug is orally or intravenously administered chemotherapy for, for example, the special neoplastic tissues, not only the therapeutic effect is low but also there is a possibility of causing a side effect to a living body since the antitumor drug diffuses into the whole body. For solving these problems, a preparation which is prepared by carrying an antitumor drug on a carrier of low toxicity having an affinity for tissues and retentivity and can be directly administered into organ-distributing blood vessels and/or lymphatics has been proposed. However, as suitable carriers, there are known liposome, erythrocyte, DNA, fibrinogen, albumin, albumin microspheres, synthetic polymers, and fats and oils but such preparations which are practically used are only the preparations on antitumor drugs showing oil-solubility by themselves, such as a sesame oil solution of epitiostanol, etc. Other many important antitumor drugs which are insoluble in oil have not yet been practically used at present since an effective solubilizing means in an oily vehicle for fats and oils has not been found.